Passivhaus Affiliate

Retrofit: How low to go? The jury says

The light-hearted, but factual debate about how far to go with energy efficiency on retrofit projects was kindly hosted by London South Bank University.

Retrofit how low to go An incremental low energy approach, Parity Projects Practical examples and the art of the possible, Bob Prewett

The evening consisted of 4 presentations each 15 minutes long discussing a range of viewpoints, Passivhaus evangelist to the non-believers and everything in-between.  with a short Q&A after each talk.

Passivhaus as the optimal solution

 Helen Brown, Encraft

Passivhaus offers a whole house approach, that  reduces carbon emissions, improves energy efficiency and addresses occupant comfort and well-being.

It provides a benchmark, raising industry standards.   

It offers deep carbon emissions reductions that are realistic and achievable now... We don't have time for small steps & wrong legacies!

Practical examples & the art of the possible

Bob Prewett, Prewett Bizley Architects

Passivhaus is a no brainer for new build projects

But it is not always the right retrofit solution for historic building, especially when external improvements are restricted.

Assessment of existing buildings is imperative and one size or standard is not a best fit for all.

Modelling of low energy options

Andy Simmonds, AECB

Must assess realistic costs of retrofit which take into account payback periods and the carbon emissions reduction.

Passivhaus is a great goal, but we must  compare to costs of other ways of decarbonising the remaining energy demand.

50-70% carbon emission reductions, over a period of 25-30 years, is a more feasible target than Passivhaus for most UK housing stock.

An incremental low-energy approach

Russell Smith, Parity Projects

Passivhaus offers a measured system and performance which gives it the upper hand, but we need to be able to improve millions of homes, and need to be able to do it in a step-by-step approach.

A series of U-values is not a way to build a building – you need a whole-house plan. Translate tangible building knowledge into home owner benefits.

What is the offer? We must start selling the comfort & health benefits.


After the presentations the following questions were posed to delegates:

1. Does the Passivhaus retrofit standard EnerPHit offer a useful exemplar for UK retrofit?

98% Yes

2. Does Passivhaus offer a methodology that can help underpin effective retrofit in the UK?

98% Yes

3. Should we adopt Passivhaus as the retrofit standard  in the UK?

Split audience - 46 No, 23 Yes, 11 undecided.


Thanks to all that attended and participate in the debate. Maybe we should always hold our Christmas event in the new year?!

Hosted by  

London South Bank University logo 

Passivhaus Trust Logo AECB logo

30th January 2015

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